Generally hole-opening operations down-hole involve the use of a hole-opening tool to enlarge a well bore. Such tools include a tool body configured for attachment at an upper end to a rotary drill string or the like and a lower end connected to a bull nose or radial member used for positioning and guiding the tool into and though the well bore to be enlarged. The tool further includes plurality of vertically extending slots each of which is configured to receive a removable cutter assembly adapted for rotation and retention therein. As the tool rotates, the cutters also rotate as a result of contact with the walls of the borehole, thus enlarging the bore to the size of the major diameter of the cutters. The bull nose serves as a guide through the previously drilled borehole. However, the previously drilled bore hole is by no means a well defined smooth or straight bore and often contains numerous cavities due to the differences in materials in the formation. It has been observed that the bull nose tip attached to the hole opening tool often jams into the crevices and sharp formations, especially in deviated holes approaching the horizontal, causing severe damage to the tool requiring retrieval and replacement of the hole opening tool. Therefore, a more reactive guide is needed to deflect the hole-opening tool around pits and in-penitratable projections.
In addition, it has also been observed that significant problems arise when attempting to insert and set casing in a bored hole. Intermediate casings are equipped with a flared flange at the lower end, extending outward between the casing outside diameter and the hole bore size, thus forming the base of the casing annulus. This flared or flanged casing must be negotiated though the bored hole and often becomes wedged or jammed in the crevices or pockets, discussed above, causing withdrawal and rotation of the casing in order to get past the obstruction. Therefore, a more reactive guide is needed to defect the casing flange around the pits and crevices. The following description of a down-hole guide tool has proved effective in solving the above-described problems.